Several loci that predispose to cancer are known, but only a few of these loci result in susceptibility to a wide range of tumor types. Families that show a high frequency of early-onset tumors of different types are being collected. These families are not consistent with any known clinically-defined cancer syndrome. Affected individuals from these families will be screened for linkage to genomic regions with known cancer-predisposing loci, and, if necessary, a genome scan will be undertaken to identify new regions of interest. Because this set of families is likely to be heterogeneous, initial concentration will be on single large pedigrees.